1. Field of the Invention
This invention relates to an apparatus for testing electrical equipment provided with multi-contact connectors, and more particularly, for an electrical connecting apparatus capable of testing without marring the conducting surface of the terminals on multi-contact connectors.
2. Discussion
Many kinds of electronic apparatus are designed, manufactured, and sold to be used in conjunction with other complex electronic equipment. Frequently much of that equipment has been made in a different location by a completely different manufacturer. Interconnection technology which has been developed over the years has produced a series of standard multi-pin connectors which are common throughout the industry. Thus, the purchaser knows that the connector on a computer printer, for example, from one source will match a receptacle on a computer from another source. An analogy can be made to the two-pronged plug on a common household electric lamp, which will match virtually any electrical receptacle in the country.
However, the voltages encountered in most electronic circuits are usually several orders of magnitude less than the 110 volts standard domestic electric service. These small voltages demand superb electric contact from one circuit to another; any contamination, corrosion, or misalignment of a single contact can result in failure of the involved circuitry.
The individual contacts on these standardized connectors are usually cylindrical, gold plated brass or other electrically conductive metal pins assembled in a regularly spaced array which fit with sliding engagement into mating receptacles of gold plated metallic tubes. Gold is usually the material of choice for all exposed surfaces of these connectors because of its superb electrical conductivity and excellent resistance to corrosion. However, gold is a relatively soft metal, and every insertion of a male connector pin into a female receptacle erodes the thin gold plate, so that after just a few cycles the underlying base metal can be exposed to atmospheric corrosion and potential subsequent circuit failure.
Thus, it is highly desirable for a manufacturer to ship to its customers connector apparatuses in an original, pristine condition, unmarred by any premature insertion into a mating receptacle. Offsetting this need is the necessity to thoroughly test the electrical circuitry of the manufactured article prior to shipment.
U.S. Pat. Nos. 2,158,630 and 3,414,814 teach spring-loaded contactors that just touch the surface of the end points of all circuit paths. U.S. Pat. No. 3,803,483 discloses a semiconductor structure for testing the inner connector networks on insulative surfaces which are to support integrated circuit chips in integrated circuit modules; and U.S. Pat. Nos. 4,225,819 and 4,232,262 disclose apparatuses for testing connectors to detect the presence of contaminating films and foreign materials on the contact terminals of a connector or the conducting fingers of a printed circuit board.
U.S. Pat. No. 4,229,691 discloses a method and apparatus for testing telephone cords which are terminated with modular plugs utilizing test probes brought into engagement with terminal blades on the plugs. U.S. Pat. No. 4,658,212 discloses an apparatus for examining the status of individual terminal pins in a connector by engaging the point of the pin with a spring driven test probe.
U.S. Pat. No. 4,734,651 discloses an apparatus for testing electrical continuity of electrical terminals of a multi-contact electrical connector by engaging a respective electrical test probe with each of the terminals and using a multiplexer to connect each test probe in turn to a continuity testing circuit under the control of a computer.
U.S. Pat. No. 4,757,254 discloses a high-speed, side access edge connector testing assembly wherein plural probe contacts are mounted to a movable, linear carriage so that the probe connectors can be moved into and out of contact with the edge connector of a unit under test.